Electrotactile display of computer graphics for blind

This completed study was supported by the National Eye Institute, grant R01-EY10019. The Project periods were 12/1/92–5/31/97, 9/30/98–9/30/04. The research took place at the University of Wisconsin-Madison, and the principal investigator was Kurt Kaczmarek.

The 49-pixel electrode array pictured consists of a 7x7 arrangement of 0.89-mm diameter, flat-topped stainless steel electrode ‘pins’, each surrounded by a 2.36-mm diameter air gap insulator. A flat stainless steel plate coplanar with the electrode pins serves as the return current path. The electrodes are  arranged on a square grid with 2.54 mm interelectrode spacing. The lower photo shows a detail of the electrode array. 

Research in this effort has shown that:

  1. Controlled, localized touch sensations can be induced via electrical stimulation on the fingertips.
  2. Subjects can identify simple geometric patterns via haptic exploration of a matrix of small electrodes embedded in a flat plate.
  3. Sensory adaptation on the fingertips is somewhat less than that on the abdomen, particularly if the fingertips are allowed to move over the surface of the electrode array.
  4. It is possible to identify small spatial patterns presented at the level of sensory threshold, whereas good pattern identification performance requires stimuli presented at 1.5 times threshold.
  5. A contrast (ratio of pattern intensity to background intensity) of at least 2 is required for good performance in identification of small spatial patterns.
  6. The timing of pulses and bursts in the stimulation waveform affects the pattern identification performance. In general, more pulses per second yield better performance. Subjects are able to estimate the correlation of tactile scatterplots presented on the fingertips.

Project Publications

Final report for both project segments, 12/1/92–5/31/97 and 9/30/98–9/30/04, includes a complete list of all publications resulting from the research.

Our Research

Founded in 1992, the Tactile Com­mu­nication & Neurorehabilitation Laboratory (TCNL) is located at the University of Wisconsin-Madison.

We are a research center that uses the experience of many different areas of science to study the theory and application of applied neuro­plasticity, the brain’s ability to re­or­ganize in response to new informa­tion, needs, and pathways.

Our research is aimed at developing solutions for sensory and motor disorder rehabilitation.